schild



(Model.)

G. I'. SCHILD AMPLIFIER. No. 800,804. 4844144844111148411884.I

O Q o O MHSSES 844 my. v 4444564 NrTnn STATES nTnNT Trice.

GEORGE F. SCHILD; OF VALLEJO, CALIFORNIA.

AMPLIFIER.

SPECIFICATION forming part of-Letters Patent No. 300,804, dated June 24,1884.

Application filed February 20, 1884. (Model.)

To @ZZ whom it may concern:

Be it known that I, Gnonen F. SCHILD, a citizen-of the United States,residing at Vallejo, in the county of Solano and the State ofCalifornia, have invented a new and useful Mathematical Instrument Ipropose to call Ampliflen77 of which the following is a specification.

My invention relates to a mathematical instrument for copying drawingsto a larger scale. Ordinarily a mathematical instrument namedpantograph7 is used for this purpose-a complicated, bulky, and costlyinstrument.

The objects of my invention are to provide a simple, small, and cheapinstrument. I attain these objects by the instrument illustrated in theaccompanying drawings, in which- Figure l gives a perspective view ofthe entire instrument; Fig. 2, a vertical section through the pivot A;Fig. 3, the plan of the pointer B; Fig. 4L, a vertical section throughthe pencil-holder C.

Similar letters referto similar parts throughout the several views.

Fig. l shows the instrument in place, ready for working. Pivot A isstationary, and to it is fastened an elastic string, D, graduated into aseries of equal divisions. Attached to this string is the movablepointer B, resting above the monogram to be copied. At the other end ofthe string the pencil-holder C is fastened, resting above the completed'enlarged copy. l

Fig. 2 is a vertical section of the pivot A. It consists of the tack Tand the nut N. The tack T consists of the plate p, at the rim of whichis fastened the eye c. Through the center of the plate ppasses the pinf, sharpened at the lower end, and forming a screw at the other end. Tothis screw fits the nut N, shaped like a spool or reel, around which theelastic string D is wound. The string D passes between a washer (notshown on the plan) under the nut N and the plate p through the eye c. Byscrewing 'the nut N down it clamps and holds the elastic stringstationary.

In Fig. 3 I show the pointer B, consisting of a thin round plate, cutoutl in such a manner as to leave a sharp point at the center, and bendin such a shape that the elastic string passes freely underneath andthrough it. By

pressing the tongue t down the pointer becomes stationary on the string.i

The pencil-holder C (shown in Fig. 4) consists of the knob G, to theunder side of which is fastened the spring s, that supports the threadedtube a, through which the pencil passes, and around which the other endof the elastic string D is fastened. y

The method of using the instrument is as follows:' The pivot A ispressed into the table or drawing-board, the elastic string D unwoundand clamped fast, when it is found that it will stretch over the entiretable or board. If the drawing is to-be copied, say, to double itsscale, the pointer B is fastened exactly midlength of the string D bycounting off the same number of divisions on both sides of the pointer.The original drawing is then put under the pointer and fastened bytacks, when it is found that by stretching the string the pointer B willpass over every part of the drawing. Then a larger paper is fastenedunder the pencil-holder C in a similar manner. The pencil-holder istaken then in the right hand, and the pencil pressed down slightly bythe incleX-nger while the pointer B is passing delicately and steadilyover every line of the original, by stretching more or less the elasticstring D. Vhile the pointer passes over from one part of the original toanother, the pressure on the pencil is relieved, the pencil is raisedfrom the paper by the spring s, and no false pencil-lines appear on thecopy. By shifting the pointer B on the string D toward the pivot A andfastening, say, at one-fourth of its length, the original will be copiedat a quadruple'scale ofthe original, or sixteen times as large. Byfastening the pointer one-fourth of the length of the string toward thepencilholder, the copy will be made only one and one half time the scaleof the original.

To facilitate the iinding vof the exact position ofthe pointer, theelastic string D is graduated by a series of black and white stripes,each one inch long.

The copy can be enlarged by this instrument to any scale or any sizerequired, and by a little practice any person will be ableto use it.

Having fully described the mathematical i11- strument for copyingdrawings, paintings, patterns, &c., on a larger scale, and which Ipropose to ca11-amp1ier, (in distinction of C, fand the elasticgraduated string D-subthe pantograph, which copies drawings alsostantially as set forth.

1o on asmallcr sca1 e,) what I do claim as my inl In Witness whcreofhereunto set my hand.

w vention7 and deslre to secure by Letters Pat- GEORGE F. SCHILD.

3 cnt, 1s-

The combination of the four principal parts composing thenstrument-nan1e1y, the tack or pivot A? the pointer B, the pencil-holderXVtnesscs:

E. A. VILLA'rs, F. R. S'rMioNToN.

